Curable Silicone Composition, Cured Product Thereof, And Optical Semiconductor Device

ABSTRACT

A curable silicone composition comprises: (A) an organopolysiloxane represented by an average unit formula; (B) an organopolysiloxane having 10 or less silicon atoms, wherein 30 to 60 mole % of all silicon atom-bonded organic groups are alkenyl groups having from 2 to 6 carbons; (C) an organopolysiloxane represented by a general formula; (D) an organopolysiloxane having at least 2 silicon atom-bonded hydrogen atoms in a molecule, wherein the content of phenyl groups in all silicon atom-bonded organic groups in this component is at least 20 mole %; (E) an organopolysiloxane having at least 2 silicon atom-bonded hydrogen atoms in a molecule, wherein the content of phenyl groups in all silicon atom-bonded organic groups in this component is less than 20 mole %; (F) a hydrosilylation reaction catalyst; (G) a white pigment; and (H) an inorganic filler other than a white pigment, has excellent formability for forming a cured product that has little discoloration and lowering of mechanical strength by heat and light, has high light reflectance, has excellent dimensional stability, and is capable of good attachment by a sealing agent used for an optical semiconductor device.

TECHNICAL FIELD

The present invention relates to a curable silicone composition, curedproduct thereof, and to an optical semiconductor device using the curedproduct as a light reflection material.

Priority is claimed on Japanese Patent Application No. 2012-021279,filed on Feb. 2, 2012, the content of which is incorporated herein byreference.

BACKGROUND ART

Curable silicone compositions that cure by a hydrosilylation reactionare used as protective agents, coating agents, lens-molding materials,light reflection materials, or the like for optical semiconductorelements in optical semiconductor devices such as photocouplers, lightemitting diodes, solid-state imaging devices, or the like. Among these,the compositions used as light reflection materials can be exemplifiedby a resin composition for a mounting package that incorporates anoptical semiconductor element, and comprises a thermosetting typeaddition reaction-capable silicone resin that has a structure wherevinyl groups or allyl groups, and hydrogen atoms are directly bonded tosilicon atoms, a platinum-type catalyst as a curing catalyst, and awhite pigment (refer to Japanese Unexamined Patent ApplicationPublication No. 2009-21394); and by an addition curable silicone resincomposition comprises a vinyl-functional organopolysiloxane having aweight average molecular weight (Mw) greater than or equal to 30,000, anorganohydrogenpolysiloxane having at least two silicon atom-bondedhydrogen atoms in a molecule, a white pigment; an inorganic filler otherthan the white pigment, a platinum metal-type catalyst; and a reactioninhibitor, wherein its cured product has a visible light averagereflectance greater than or equal to 80% (refer to Japanese UnexaminedPatent Application Publication No. 2011-140550).

These compositions have the following problems in transfer molding,injection molding, or compression molding: low mold filling, facilegeneration of voids and flashing, and/or a poor mold releasability;also, slow curing rate and a poor workability in the molding operation.In addition, although the cured products obtained by curing thesecompositions have the advantage of little discoloration by heat andlight, the cured products have following problems of high linearexpansion coefficients and/or a low mechanical strength at hightemperature, as well as the problems of an insufficient lightreflectance and great lowering of mechanical strength by heat or light.When such a composition is used to form alight reflection material in anoptical semiconductor device, and when a sealing agent covers theoptical semiconductor element, adhesion of the sealing agent to thelight reflection material is poor.

An object of the present invention is to provide a curable siliconecomposition that has excellent moldability and that forms a curedproduct that has little discoloration and lowering of mechanicalstrength by heat and light, has high light reflectance, and hasexcellent dimensional stability. A further object of the presentinvention is to provide a cured product that has little discolorationand lowering of mechanical strength by heat and light, and has highlight reflectance. A further object of the present invention is toprovide an optical semiconductor device in which a sealing agent bondswell to a light reflection material.

DISCLOSURE OF INVENTION

The curable silicone composition of the present inventioncharacteristically comprises:

-   (A) 100 parts by mass of an organopolysiloxane represented by the    following average unit formula:

(R¹ ₃SiO_(1/2))_(a)(R¹₂SiO_(2/2))_(b)(R¹SiO_(3/2))_(c)(SiO_(4/2))_(d)(R²O_(1/2))_(e)

wherein R¹ are the same or different, and are phenyl groups, alkylgroups having from 1 to 6 carbons, or alkenyl groups having from 2 to 6carbons, provided that 30 to 80 mole % of all R¹ are phenyl groups, and5 to 20 mole % of all R¹ are alkenyl groups; R² is a hydrogen atom oralkyl group having from 1 to 6 carbons; and “a”, “b”, “c”, “d”, and “e”are numbers that respectively satisfy: 0≦a≦0.3, 0≦b≦0.7, 0.3≦c≦0.9,0≦d≦0.1, 0≦e≦0.1, and a+b+c+d=1;

-   (B) 5 to 50 parts by mass of an organopolysiloxane having 10 or less    silicon atoms, wherein 30 to 60 mole % of all silicon atom-bonded    organic groups in this component are alkenyl groups having from 2 to    6 carbons;-   (C) 0 to 40 parts by mass of an organopolysiloxane represented by    the following general formula:

R³ ₃SiO(R³ ₂SiO)_(m)SiR³ ₃

-   -   wherein R³ are the same or different, and are phenyl groups,        alkyl groups having from 1 to 6 carbons, or alkenyl groups        having from 2 to 6 carbons, provided that 30 to 70 mole % of all        R³ are phenyl groups, and at least one R³ is an alkenyl group;        and “m” is an integer in a range from 10 to 100;

-   (D) an organopolysiloxane having at least 2 silicon atom-bonded    hydrogen atoms in a molecule, wherein a content of phenyl groups in    all silicon atom-bonded organic groups in this component is at least    20 mole %, in an amount that provides 0.3 to 1.5 moles of silicon    atom-bonded hydrogen atoms in this component per 1 mole of the total    amount of alkenyl groups in components (A) to (C);

-   (E) an organopolysiloxane having at least 2 silicon atom-bonded    hydrogen atoms in a molecule, wherein a content of phenyl groups in    all silicon atom-bonded organic groups in this component is less    than 20 mole %, in an amount that provides 0.2 to 0.8 moles of    silicon atom-bonded hydrogen atoms in this component per 1 mole of    the total amount of alkenyl groups in components (A) to (C);

-   (F) a hydrosilylation reaction catalyst in a quantity sufficient to    accelerate the hydrosilylation reaction between the alkenyl groups    in components (A) to (C) and the silicon atom-bonded hydrogen atoms    in components (D) and (E);

-   (G) a white pigment in an amount of at least 25 parts by mass per    100 parts by mass of the total amount of components (A) to (F); and

-   (H) an inorganic filler other than a white pigment in an amount of    at least 40 parts by mass per 100 parts by mass of the total amount    of components (A) to (F),    wherein the content of the total amount of components (G), and (H)    is not more than 300 parts by mass per 100 parts by mass of the    total amount of components (A) to (F).

Moreover, the cured product of the present invention ischaracteristically provided by curing the aforementioned curablesilicone composition.

Furthermore, the optical semiconductor device of the present inventionis characterized in comprising: an optical semiconductor element, alight reflection material for reflecting light emitted from the element,and a sealing agent for sealing the element that contacts the lightreflection material; wherein the light reflection material is formed bya cured product of the aforementioned curable silicone composition.

Effects of Invention

The curable silicone composition of the present invention ischaracterized by an excellent moldability and upon curingcharacteristically forms a cured product that exhibits littlediscoloration or lowering of mechanical strength by heat or light, andhas high light reflectance and excellent dimensional stability.Moreover, the cured product of the present invention characteristicallyexhibits little discoloration or lowering of mechanical strength by heator light, and has high light reflectance. Furthermore, in the opticalsemiconductor device of the present invention, the sealing agent readilybonds to the light reflection material.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of an LED as one example of the opticalsemiconductor device of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Firstly, the curable silicone composition of the present invention willbe explained in detail.

Component (A) is the main component of the present composition and is anorganopolysiloxane represented by the following average unit formula:

(R¹ ₃SiO_(1/2))_(a)(R¹₂SiO_(2/2))_(b)(R¹SiO_(3/2))_(c)(SiO_(4/2))_(d)(R²O_(1/2))_(e)

In the formula, R¹ are the same or different, and are phenyl groups,alkyl groups having from 1 to 6 carbons, or alkenyl groups having from 2to 6 carbons. Examples of the alkyl group of R¹ include methyl groups,ethyl groups, propyl groups, butyl groups, pentyl groups, hexyl groups,cyclopentyl groups, and cyclohexyl groups. Examples of the alkenyl groupof R¹ include vinyl groups, allyl groups, butenyl groups, pentenylgroups, and hexenyl groups. In the formula, the content of phenyl groupsin all R¹ is in a range from 30 to 80 mole %, and is preferably in arange from 40 to 70 mole %. When the content of phenyl groups is greaterthan or equal to the lower limit of the aforementioned range, mechanicalstrength of the obtained cured product is good. On the other hand, whenthe content of phenyl groups is less than or equal to the aforementionedupper limit, hardness of the obtained cured product is good at hightemperature. Moreover, in the formula, the content of alkenyl groups inall R¹ is in a range from 5 to 20 mole %. When the content of alkenylgroups is greater than or equal to the lower limit of the aforementionedrange, hardness of the obtained cured product at room temperature isgood. On the other hand, when the content of alkenyl groups is less thanor equal to the upper limit of the aforementioned range, mechanicalstrength of the obtained cured product is good.

Moreover, R² in the formula is a hydrogen atom or alkyl group havingfrom 1 to 6 carbons. Examples of the alkyl group of R² include methylgroups, ethyl groups, propyl groups, butyl groups, pentyl groups, andhexyl groups.

Moreover, in the formula, “a” is a number indicating the fraction ofsiloxane units represented by the general formula: R¹ ₃SiO_(1/2), and isa number satisfying: 0≦a≦0.3, and preferably 0≦a≦0.25. When the value of“a” is less than or equal to the aforementioned upper limit, hardness ofthe obtained cured product at room temperature is good. Moreover, “b” isa number indicating the fraction of siloxane units represented by thegeneral formula: R¹ ₂SiO_(2/2), and is a number satisfying: 0≦b≦0.7, andpreferably 0≦b≦0.6. When the value of “b” is less than or equal to theaforementioned upper limit, hardness of the obtained cured product atroom temperature is good. Moreover, “c” is a number indicating thefraction of siloxane units represented by the general formula:R¹SiO_(3/2), and is a number satisfying: 0.3≦c≦0.9, and preferably0.35≦c≦0.85. When the value of “c” is greater than or equal to the lowerlimit of the aforementioned range, hardness of the obtained curedproduct at room temperature is good. On the other hand, when the valueof “c” is less than or equal to the upper limit of the aforementionedrange, mechanical strength of the obtained cured product is good.Moreover, “d” is a number indicating the fraction of siloxane unitsrepresented by the general formula: SiO_(4/2), and is a numbersatisfying: 0≦d≦0.1. When the value of “d” is less than or equal to theupper limit of the aforementioned range, mechanical strength of theobtained cured product is good. Moreover, “e” is a number indicating thefraction of units represented by the general formula: R²O_(1/2), and isa number satisfying: 0≦e≦0.1. When the value of “e” is less than orequal to the aforementioned upper limit, hardness of the obtained curedproduct at room temperature is good. Furthermore, the sum of “a”, “b”,“c”, and “d” in the formula is 1.

Component (B) is a component used for improving handling andprocessability of the present composition and adjusting hardness of theobtained cured product. Component (B) is an organopolysiloxane having 10or less silicon atoms, wherein 30 to 60 mole % of all siliconatom-bonded organic groups in this component are alkenyl groups havingfrom 2 to 6 carbons. Examples of the alkenyl groups in component (B)include vinyl groups, allyl groups, butenyl groups, pentenyl groups, andhexenyl groups. Although no particular limitation is placed on thesilicon-bonded organic group other than the alkenyl groups in component(B), this group is exemplified by methyl group and phenyl group, andpreferably is methyl group. 30 to 60 mole % of all silicon atom-bondedorganic groups are alkenyl groups having from 2 to 6 carbons. When thecontent of alkenyl groups is greater than or equal to the lower limit ofthe aforementioned range, hardness of the obtained cured product isgood. On the other hand, when the content of alkenyl group is less thanor equal to the upper limit of the aforementioned range, mechanicalstrength of the obtained cured product is good. Furthermore, the numberof silicon atoms is less than or equal to 10. This is because viscosityof the composition is good when the number of silicon atoms is less thanor equal to 10.

Examples of component (B) include1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane,tetrakis(dimethylvinylsiloxy)silane,methyltris(dimethylvinylsiloxy)silane, andphenyltris(dimethylvinylsiloxy)silane.

The content of component (B) in the present composition, per 100 partsby mass of component (A), is in a range from 5 to 50 parts by mass, andis preferably in a range from 5 to 40 parts by mass. When the content ofcomponent (B) is greater than or equal to the lower limit of theaforementioned range, viscosity of the composition is good. On the otherhand, when the content of component (B) is less than or equal to theupper limit of the aforementioned range, mechanical strength of theobtained cured product is good.

Component (C) is an optional component for adjusting viscosity of thepresent composition and for adjusting hardness and mechanical strengthof the obtained cured product. Component (C) is an organopolysiloxanerepresented by the following general formula:

R³ ₃SiO(R³ ₂SiO)_(m)SiR³ ₃

In the formula, R³ are the same or different, and are phenyl groups,alkyl groups having from 1 to 6 carbons, or alkenyl groups having from 2to 6 carbons.

Examples of the alkyl group of R³ include methyl groups, ethyl groups,propyl groups, butyl groups, pentyl groups, hexyl groups, cyclopentylgroups, and cyclohexyl groups. Examples of the alkenyl group of R³include vinyl groups, allyl groups, butenyl groups, pentenyl groups, andhexenyl groups. In the formula, the content of phenyl groups in all R³is in a range from 30 to 70 mole %, and is preferably in a range from 40to 60 mole %. When the content of phenyl groups is greater than or equalto the lower limit of the aforementioned range, mechanical strength ofthe obtained cured product is good. On the other hand, when the contentof phenyl groups is greater than or equal to the aforementioned upperlimit, hardness of the obtained cured product is good. Moreover, atleast one R³ is an alkenyl group. This component participates in thecuring reaction when this component has at least one alkenyl group.

In the formula, “m” is an integer in a range from 10 to 100, and ispreferably an integer in a range from 10 to 50. When “m” is greater thanor equal to the lower limit of the aforementioned range, mechanicalstrength of the obtained cured product is good. On the other hand, when“m” is less than or equal to the upper limit of the aforementionedrange, handling and processability of the obtained composition is good.

The content of component (C) in the present composition, per 100 partsby mass of component (A), is in a range from 0 to 40 parts by mass, andis preferably in a range from 0 to 20 parts by mass. When the content ofcomponent (C) is less than or equal to the aforementioned upper limit,hardness of the obtained cured product is good.

Component (D) is a first crosslinking agent of the present composition,and is an organopolysiloxane having at least 2 silicon atom-bondedhydrogen atoms in a molecule, wherein at least 20 mole % of all siliconatom-bonded organic groups in this component are phenyl groups. Thenumber of the silicon atom-bonded hydrogen atoms in a molecule incomponent (D) is greater than or equal to 2. If this number of thesilicon atom-bonded hydrogen atoms is present, crosslinking for curingis sufficient, and hardness of the obtained cured product is good.Examples of the silicon-bonded organic group in component (D) include amonovalent hydrocarbon group having no unsaturated aliphatic bond, asexemplified by an alkyl group such as a methyl group, ethyl group,propyl group, butyl group, pentyl group, hexyl group, heptyl group,cyclopentyl group, cyclohexyl group, cycloheptyl group, and the like; anaryl group such as a phenyl group, tolyl group, xylyl group, and thelike; and an aralkyl group such as a benzyl group, phenethyl group, andthe like. Of these, a phenyl group and an alkyl group having from 1 to 6carbons are preferred. The content of phenyl groups in all siliconatom-bonded organic groups in component (D) is greater than or equal to20 mole %, and is preferably from 20 to 70 mole %. When the content ofphenyl groups is greater than or equal to the lower limit of theaforementioned range, mechanical strength of the obtained cured productat high temperature is good. On the other hand, when the content ofphenyl groups is less than or equal to the aforementioned upper limit,mechanical strength of the obtained cured product is good.

Examples of component (D) include an organotrisiloxane represented bythe following general formula:

(HR⁴ ₂SiO)₂SiR⁴ ₂

a linear chain organopolysiloxane represented by the following generalformula:

R⁵ ₃SiO(R⁵ ₂SiO)_(n)SiR⁵ ₃

and a branched chain organopolysiloxane represented by the followingaverage unit formula:

(R⁵SiO_(3/2))_(f)(R⁵ ₂SiO_(2/2))_(g)(R⁵₃SiO_(1/2))_(h)(SiO_(4/2))_(i)(XO_(1/2))_(j)

In the formula, R⁴ are the same or different, and are phenyl groups oralkyl groups having from 1 to 6 carbons. Examples of the alkyl group ofR⁴ include methyl groups, ethyl groups, propyl groups, butyl groups,pentyl groups, hexyl groups, cyclopentyl groups, and cyclohexyl groups.The content of phenyl groups in all R⁴ is greater than or equal to 20mole %, and is preferably in a range from 20 to 70 mole %.

In the formula, R⁵ are the same or different, and are hydrogen atoms,phenyl groups, or alkyl groups having from 1 to 6 carbons. At least twoR⁵ in the formula are hydrogen atoms. Examples of the alkyl group of R⁵include methyl groups, ethyl groups, propyl groups, butyl groups, pentylgroups, hexyl groups, cyclopentyl groups, and cyclohexyl groups. Thecontent of phenyl groups in all R⁵ except hydrogen atoms is greater thanor equal to 20 mole %, and is preferably in a range from 20 to 70 mole%.

In the formula, “n” is an integer in a range from 5 to 1,000. In theformula, “f” is a positive number, “g” is 0 or a positive number, “h” is0 or a positive number, “i” is 0 or a positive number, and “j” is 0 or apositive number. Also, the ratio “g/f” is a number in a range from 0 to10. The ratio “h/f” is a number in a range from 0 to 5. The ratio“i/(f+g+h+i)” is a number in a range from 0 to 0.3. The ratio“j/(f+g+h+i)” is a number in a range from 0 to 0.4.

All of component (D) or the main component of component (D) ispreferably an organotrisiloxane represented by the following generalformula:

(HR⁴ ₂SiO)₂SiR⁴ ₂.

Content of this organotrisiloxane in component (D) is preferably atleast 50% by mass.

The content of component (D) in the present composition is an amountsuch that the amount of silicon atom-bonded hydrogen atoms in thiscomponent, per 1 mole of the total amount of alkenyl groups incomponents (A) to (C), is from 0.3 to 1.5 moles, and is preferably from0.5 to 1.2 moles. When the content of component (D) is within theaforementioned range, hardness of the obtained cured product is good.

Component (E) is a second crosslinking agent of the present composition,and is an organopolysiloxane having at least 2 silicon atom-bondedhydrogen atoms in a molecule, wherein the content of phenyl groups inall silicon atom-bonded organic groups in this component is less than 20mole %. The number of the silicon atom-bonded hydrogen atoms in amolecule in component (E) is greater than or equal to 2. If this numberof the silicon atom-bonded hydrogen atoms is present, crosslinking forcuring is sufficient, and hardness of the obtained cured product isgood. Examples of the silicon-bonded organic group in component (E)include a monovalent hydrocarbon group having no unsaturated aliphaticbond, as exemplified by an alkyl group such as a methyl group, ethylgroup, propyl group, butyl group, pentyl group, hexyl group, heptylgroup, cyclopentyl group, cyclohexyl group, cycloheptyl group, and thelike; an aryl group such as a phenyl group, tolyl group, xylyl group,and the like; and an aralkyl group such as a benzyl group, phenethylgroup, and the like. Of these, a phenyl group and an alkyl group havingfrom 1 to 6 carbons are preferred. The content of phenyl groups in allsilicon atom-bonded organic groups in component (E) is less than 20 mole%, and is preferably less than or equal to 10 mole %. Particularlypreferably, at least 90 mole % of all silicon atom-bonded organic groupsin component (E) are methyl groups. When the content of phenyl groups isless than the upper limit of the aforementioned range and particularlywhen the methyl group content is greater than or equal to the lowerlimit of the aforementioned range, adhesion of the obtained curedproduct toward various types of substrates is good, and adhesion of thesealing agent used for an optical semiconductor device to the curedproduct is good.

Examples of component (E) include a cyclic organopolysiloxanerepresented by the following formula:

(MeHSiO)_(p)

wherein “Me” is a methyl group, and “p” is an integer in a range from 4to 8, and linear chain organopolysiloxanes represented by the followinggeneral formulae:

Me₃SiO(MeHSiO)_(q)SiMe₃

Me₃SiO(MeHSiO)_(r)(Me₂SiO)_(s)SiMe₃

wherein “Me” is a methyl group; “q” is an integer greater than or equalto 5; “r” and “s” are respective integers greater than or equal to 5;and “r” is equal to or greater than “s”.

The content of component (E) in the present composition is an amountsuch that the amount of silicon atom-bonded hydrogen atoms in thiscomponent, per 1 mole of total alkenyl groups in components (A) to (C),is from 0.2 to 0.8 moles, and is preferably from 0.3 to 0.7 moles.Adhesion of the sealing agent used for an optical semiconductor deviceto the obtained cured product becomes good when the content of component(E) is within the aforementioned range.

The total content of components (D) and (E) in the present composition,per 1 mole of total alkenyl groups in components (A) to (C), ispreferably in a range such that the total silicon atom-bonded hydrogenatoms in components (D) and (E) is in a range from 0.5 to 2.0 moles, andparticularly preferably in a range from 0.5 to 1.5 moles. When the totalcontent of components (D) and (E) is within the aforementioned range,hardness of the obtained cured product is good.

Component (F) is a hydrosilylation reaction catalyst for acceleratingthe hydrosilylation reaction between the alkenyl groups in components(A) to (C) and the silicon atom-bonded hydrogen atoms in components (D)and (E). Examples of component (F) include platinum-type catalysts,rhodium-type catalysts, and palladium-type catalysts. Platinum-typecatalysts are preferred due to the ability to remarkably acceleratecuring of the composition. Examples of the platinum-type catalystsinclude platinum fine powder, chloroplatinic acid, alcoholic solutionsof chloroplatinic acid, platinum-alkenylsiloxane complexes,platinum-olefin complexes, and platinum-carbonyl complexes.Platinum-alkenylsiloxane complexes are particularly preferred. Examplesof the alkenylsiloxane include1,3-divinyl-1,1,3,3-tetramethyldisiloxane,1,3,5,7-tetramethyl-1,3,5,7-tetravinyl cyclotetrasiloxane,alkenylsiloxanes having part of the methyl groups of thesealkenylsiloxane substituted by ethyl groups, phenyl groups, or the like,and alkenylsiloxanes having vinyl groups of these alkenylsiloxanesubstituted by allyl groups, hexenyl groups, or the like.1,3-divinyl-1,1,3,3-tetramethyldisiloxane is particularly preferred dueto high stability of the platinum-alkenylsiloxane complex. Due to theability for improving the stability of the platinum-alkenylsiloxanecomplexes, combination is recommended of the platinum-alkenylsiloxanecomplexes with organosiloxane oligomers such as1,3-divinyl-1,1,3,3-tetramethyldisiloxane,1,3-diallyl-1,1,3,3-tetramethyldisiloxane,1,3-divinyl-1,3-dimethyl-1,3-diphenyldisiloxane,1,3-divinyl-1,1,3,3-tetraphenyldisiloxane,1,3,5,7-tetramethyl-1,3,5,7-tetravinyl cyclotetrasiloxane, or the likealkenylsiloxane, or dimethylsiloxane oligomers. The addition ofalkenylsiloxanes is particularly preferred.

No particular limitation is placed on the content of component (F) inthe composition as long as there is an amount sufficient to acceleratethe hydrosilylation reaction between the alkenyl groups in components(A) to (C) and the silicon atom-bonded hydrogen atoms in components (D)and (E). However, this concentration in the present composition, interms of mass units, based on the metal atoms in component (F), ispreferably from 0.01 to 500 ppm, further is preferably from 0.01 to 100ppm, and particularly is preferably from 0.01 to 50 ppm. When thecontent of component (F) is greater than or equal to the lower limit ofthe aforementioned range, the obtained composition exhibits an excellentcure. On the other hand, when the content of component (F) is less thanor equal to the upper limit of the aforementioned range, the obtainedcured product is resistant to discoloration.

Component (G) is a white pigment for coloring the cured product andcomposition of the present invention white and for increasing lightreflectance. Preferred examples of component (G) include metal oxidessuch as titanium oxide, alumina, zinc oxide, zirconium oxide, magnesiumoxide, and the like; barium sulfate, zinc sulfate, or the like; andtitanium oxide and zinc oxide are particularly preferred.

Although no particular limitation is placed on the shape and the averageparticle diameter of component (G), the average particle diameter ispreferably in a range from 0.05 to 10.0 μm, and further is preferably ina range from 0.1 to 5.0 μm. In order to increase the compatibility anddispersion ability of the white pigment with the resin and inorganicfiller, the white pigment may be surface-treated using a silane couplingagent, silica, alumina, or the like.

The content of component (G) in the present composition, per 100 partsby mass of the total amount of components (A) to (F), is greater than orequal to 25 parts by mass, and is preferably greater than or equal to 30parts by mass. Light reflectance of the cured product is good when thecontent of component (G) is greater than or equal to the lower limit ofthe aforementioned range.

Component (H) is an inorganic filler other than a white pigment fordecreasing linear expansion coefficient of the cured product of thepresent invention, for improvement of dimensional stability, and forimparting appropriate viscosity to the composition. The inorganic fillerof component (H) is exemplified by spherical silica, non-sphericalsilica, glass fiber, mica, and calcium carbonate. Examples of thespherical silica include dry-process silica, precipitated silica, fusedsilica, and pyrogenic silica. Examples of the spherical silica includequartz powder and glass beads. Examples of the glass fiber includechopped glass fibers and milled glass fibers.

Although no particular limitation is placed on average particle diameterof the inorganic filler of component (H), in the case of spheres, theaverage particle diameter is preferably in a range from 0.1 to 20 μm,and further is preferably in a range from 0.5 to 10 μm. In the case offibers, fiber diameter is preferably in a range from 1 to 50 μm, andfurther preferably is in a range from 5 to 20 μm. Fiber length ispreferably in a range from 5 to 500 μm, and further is preferably in arange from 10 to 300 μm.

The content of component (H) in the present composition, per 100 partsby mass of the total amount of components (A) to (F), is greater than orequal to 40 parts by mass, and is preferably greater than or equal to 50parts by mass. Linear expansion coefficient of the obtained curedproduct is low and dimensional stability is good when the content ofcomponent (H) is greater than or equal to the lower limit of theaforementioned range.

The total content of components (G) and (H) in the present composition,per 100 parts by mass of the total amount of components (A) to (F), isless than or equal to 300 parts by mass, and is preferably less than orequal to 250 parts by mass. Viscosity of the obtained composition isgood when the total content of components (G) and (H) is less than orequal to the aforementioned upper limit.

Although the aforementioned components (A) to (H) are essentialcomponents of the present composition, other optional components includea reaction inhibitor, for example, alkyne alcohols such as1-ethynyl-1-cyclohexanol, 2-methyl-3-butyn-2-ol,3,5-dimethyl-1-hexyn-3-ol, 2-phenyl-3-butyn-2-ol, and the like; eneynecompounds such as 3-methyl-3-penten-1-yne, 3,5-dimethyl-3-hexen-1-yne;1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane,1,3,5,7-tetramethyl-1,3,5,7-tetrahexenylcyclotetrasiloxane,benzotriazole, and the like. Although no limitation is placed on thecontent of this reaction inhibitor, the content in the presentcomposition, in terms of mass units, is preferably in a range from 1 to5,000 ppm.

The present composition preferably includes an adhesion promoter inorder to further improve adhesion to the substrate under contact duringcuring. This adhesion promoter is exemplified by: organosilanes ororganosiloxane oligomers having about 4 to 20 silicon atoms and alinear, branched, or cyclic structure and having a trialkoxysiloxy group(e.g., trimethoxysiloxy group or triethoxysiloxy group) ortrialkoxysilylalkyl group (e.g., trimethoxysilylethyl group ortriethoxysilylethyl group) and a hydrosilyl group or alkenyl group(e.g., vinyl group or allyl group); organosilanes or organosiloxaneoligomers having about 4 to 20 silicon atoms and a linear, branched, orcyclic structure and having a trialkoxysiloxy group ortrialkoxysilylalkyl group and a methacryloxyalkyl group (e.g.,3-methacryloxypropyl group); organosilanes or organosiloxane oligomershaving about 4 to 20 silicon atoms and a linear, branched, or cyclicstructure and having a trialkoxysiloxy group or trialkoxysilylalkylgroup and an epoxy group-bonded alkyl group (e.g., 3-glycidoxypropylgroup, 4-glycidoxybutyl group, 2-(3,4-epoxycyclohexyl)ethyl group, or3-(3,4-epoxycyclohexyl)propyl group); and products of reaction betweenaminoalkyltrialkoxysilanes and epoxy group-bonded alkyltrialkoxysilanes,and epoxy group-containing ethyl polysilicate. Specific examples of theadhesion promoter include: vinyltrimethoxysilane, allyltrimethoxysilane,allyltriethoxysilane, hydrogentriethoxysilane,3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane,2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane,3-methacryloxypropyltrimethoxysilane,3-methacryloxypropyltriethoxysilane, products of reaction between3-glycidoxypropyltriethoxysilane and 3-aminopropyltriethoxysilane,products of condensation reaction between silanol group-chain terminatedmethylvinylsiloxane oligomers and 3-glycidoxypropyltrimethoxysilane,products of condensation reaction between silanol group-chain terminatedmethylvinylsiloxane oligomers and 3-methacryloxypropyltriethoxysilane,and tris(3-trimethoxysilylpropyl) isocyanate.

As long as the object of the present invention is not impaired, otheroptional components may be included in the present composition. Suchother optional components include organic resin powders ofpolymethacrylate resins, silicone resins, or the like; carnauba wax,metal stearate salts, methyl silicone oils, or the like mold releaseagents; and thermal stabilizers, flame retardants, solvents, or thelike.

Although no particular limitation is placed on the viscosity of thepresent composition at 25° C., the viscosity is preferably in a rangefrom 5 to 200 Pa·s, further is preferably in a range from 5 to 120 Pa·s,and particularly is preferably in a range from 10 to 80 Pa·s. Theoccurrence of flashing in the obtained molded product is suppressed whenthe viscosity is greater than or equal to the lower limit of theaforementioned range. Handling and processability of the obtainedcomposition is good when viscosity is less than or equal to the upperlimit of the aforementioned range.

Although no particular limitation is placed on the hardness of the curedproduct of the present invention, type D durometer hardness as specifiedby JIS K 7215-1986 “Testing Methods for Durometer Hardness of Plastics”is preferably greater than or equal to 60, further is preferably greaterthan or equal to 65, and particularly is preferably greater than orequal to 70. Dimensional stability of the cured product improves andresistance to deformation of the cured product increases when hardnessis greater than or equal to the lower limit of the aforementioned range.Although no particular limitation is placed on the bending hardness ofthe cured product of the present composition, bending hardness asspecified by JIS K 6911-1995 “General Testing Methods of ThermosettingPlastics” is preferably greater than or equal to 5 MPa, further ispreferably greater than or equal to 7 MPa, and particularly preferablyis greater than or equal to 10 MPa. Mechanical strength of the curedproduct is good, and the cured product becomes resistant to cracking orthe like, when bending hardness is greater than or equal to the lowerlimit of the aforementioned range.

Although no particular limitation is placed on reflectance of the curedproduct of the present invention, total luminous reflectance as measuredaccording to the method stipulated in JIS K 7375: 2008“Plastics—Determination of Total Luminous Transmittance and Reflectance”is preferably greater than or equal to 80%, and particularly ispreferably greater than or equal to 90%. Although no particularlimitation is placed on the linear expansion coefficient of the curedproduct of the present composition, the linear expansion coefficientmeasured according to the method stipulated in JIS K 7197-1991 “TestingMethod for Linear Thermal Expansion Coefficient of Plastics byThermomechanical Analysis” in the temperature range of 25 to 200° C. hasan average value that is preferably less than or equal to 200 ppm/° C.,and particularly is preferably less than or equal to 150 ppm/° C.

Although the curing reaction of the present composition progresses atroom temperature or by heating, the composition of the present inventionis preferably heated to cause rapid curing. Heating temperature ispreferably in a range from 50 to 200° C., and further is preferably in arange from 100 to 150° C. The molding method of the present compositionis exemplified by transfer molding, injection molding, and compressionmolding.

The cured product of the present invention will be explained next indetail.

The cured product of the present invention is obtained by curing theaforementioned composition. The cured product of the present inventionpreferably has characteristics as described above.

The optical semiconductor device of the present invention will beexplained next in detail.

The optical semiconductor device of the present invention ischaracterized by comprising: an optical semiconductor element, a lightreflection material for reflecting light emitted from the element, and asealing agent for sealing the element that contacts the light reflectionmaterial; wherein the light reflection material is formed by a curedproduct of the curable silicone composition. This type of opticalsemiconductor device is exemplified by a light emitting diode (LED). Thelight reflection material in this optical semiconductor device functionsas a packaging material of the optical semiconductor device.

FIG. 1 shows a cross-sectional view of a surface mounted type LED, whichis one example of the semiconductor device of the present invention. Inthe LED shown in FIG. 1, the optical semiconductor element 1 is diebonded to a lead frame 2 by a die bonding material, and lead frames 2,3and this optical semiconductor element 1 are further wire bonded to thelead frame 2,3 by bonding wires 4,4′. At the periphery of this opticalsemiconductor element 1, with the exception of the upper part thereof, alight reflection material 5 composed of the cured product formed fromthe aforementioned curable silicone composition is present. The opticalsemiconductor element 1 within this light reflection material 5 issealed by the sealing agent 6. This sealing agent is exemplified bysilicone type and epoxy type sealing agents, and this sealing agent ispreferably a silicone type sealing agent. This silicone type sealingagent is exemplified by methyl silicone type sealing agents manufacturedby Dow Corning Toray Co., Ltd. (product names: OE-6370HF, EG-6301,OE-6351, and OE-6336) and phenylmethyl silicone type sealing agentsmanufactured by Dow Corning Toray Co., Ltd. (product names: OE-6630,OE-6635, OE-6665, and OE-6550).

The method of production of the surface mounted type LED shown in FIG. 1is exemplified by a method including the steps of: (1) forming a lightreflection material 5 integrated with the lead frames 2,3 by compressionmolding or transfer molding of the curable silicone composition, (2) diebonding of the optical semiconductor element 1 on the lead frame 2 usinga die bonding material, (3) wire bonding the optical semiconductorelement 1 and the lead frames 2,3 using bonding wires 4,4′, and (4)sealing the optical semiconductor element 1 using the sealing agent 6.

EXAMPLES

The curable silicone composition, cured product thereof, and opticalsemiconductor device of the present invention will be explained infurther detail using practical examples. Viscosity values in theexamples are values at 25° C. Moreover, in the formulae, “Me”, “Ph”, and“Vi” respectively represent the methyl group, phenyl group, and vinylgroup. Characteristics of the cured product were measured in the belowdescribed manner.

[Hardness]

Hardness of the cured product was measured by a type D durometer asspecified in JIS K 7215-1986 “Testing Methods for Durometer Hardness ofPlastics.”

[Bending Strength]

Bending strength of the cured product was measured according to themethod specified in JIS K 6911-1995 “General Testing Methods ofThermosetting Plastics.”

[Total Luminous Reflectance]

Total luminous reflectance of the cured product was measured by themethod specified in JIS K 7375:2008 “Plastics—Determination of TotalLuminous Transmittance and Reflectance.”

[Linear Expansion Coefficient]

Average linear expansion coefficient of the cured product in thetemperature range of 25 to 200° C. was measured by the method specifiedin JIS K 7197-1991 “Testing Method for Linear Thermal ExpansionCoefficient of Plastics by Thermomechanical Analysis.”

Moreover, adhesion of the sealing agent of the light reflection materialin the optical semiconductor device was evaluated in the followingmanner.

[Adhesion of the Sealing Agent to the Light Reflection Material]

By transfer molding at 120° C. using the curable silicone composition, acasing was formed from a light reflection material on a silver-platedlead frame. Thereafter, the cavity of each casing was filed using asealing agent, the assembly was heated and cured for 2 hours at 150° C.,and 20 of the optical semiconductor devices shown in FIG. 1 wereproduced. A methyl silicone type sealing agent manufactured by DowCorning Toray Co., Ltd. (product name: OE-6370HF) or a phenylmethylsilicone type sealing agent manufactured by Dow Corning Toray Co., Ltd.(product name: OE-6630) was used as the sealing agent. After thisoptical semiconductor device was used for solder reflow testing for 30seconds at 260° C., the bonded state of the sealing agent of the lightreflection material was observed by red ink testing. That is to say,after 24 hours of immersion of the semiconductor device in red inksolution (INK-350-R, manufactured by Pilot Corporation), the opticalsemiconductor device was washed using water, and the presence or absenceof penetration of ink into the contact interface between the lightreflection material and the sealing agent was visually checked.

Practical Example 1

100 parts by mass of a methylvinylphenylpolysiloxane represented by thefollowing average unit formula:

(MeViSiO_(2/2))_(0.15)(Me₂SiO_(2/2))_(0.15)(Ph₂SiO_(2/2))_(0.30)(PhSiO_(3/2))_(0.40)(HO_(1/2))_(0.04)

25 parts by mass of1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane represented bythe following formula:

(MeViSiO)₄

50 parts by mass of 1,1,5,5-tetramethyl-3,3-diphenyltrisiloxanerepresented by the following formula:

(HMe₂SiO)₂SiPh₂

in an amount that provides 0.81 moles of silicon atom-bonded hydrogenatoms in this component per 1 mole of the total amount of vinyl groupsin the aforementioned methylvinylphenylpolysiloxane and1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane, 6 parts bymass of 1,3,5,7-tetramethylcyclotetrasiloxane represented by thefollowing formula:

(MeHSiO)₄

in an amount that provides 0.25 moles of silicon atom-bonded hydrogenatoms in this component per 1 mole of the total amount of vinyl groupsin the aforementioned methylvinylphenylpolysiloxane and1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane,1,3-divinyl-1,1,3,3-tetramethyldisiloxane solution of1,3-divinyl-1,1,3,3-tetramethyldisiloxane complex of platinum in anamount that provides 3.5 ppm of the platinum metal in terms of massunits in the present composition, 1-ethynyl-1-cyclohexanol in an amountthat provides 200 ppm in terms of mass units in the present composition,100 parts by mass of titanium oxide having an average primary particlediameter of 0.2 μm (SX-3103, manufactured by Sakai Chemical IndustryCo., Ltd.), 135 parts by mass of crushed quartz powder having an averageparticle diameter of 5 μM (CRYSTALITE VX-52, manufactured by TatsumoriLtd.), and 110 parts by mass of spherical silica having 15 μm averageparticle diameter (HS-202, manufactured by Nippon Steel & SumikinMaterials Co., Ltd.) were blended to prepare a curable siliconecomposition that had a viscosity of 32 Pa·s.

This composition was heated for 2 hours at 150° C. to form a curedproduct. This cured product had a type D durometer hardness of 78, abending strength of 9.3 MPa, a total luminous reflectance of 94.7%, anda linear expansion coefficient of 115 ppm/° C. The optical semiconductordevice shown in FIG. 1 was produced using this composition. Flashing andvoids were not observed in this optical semiconductor device. No peelingwas observed of the sealing agent from the light reflection material inoptical semiconductor devices using either OE-6370HF or OE-6630 as thesealing agent materials.

Practical Example 2

100 parts by mass of a methylvinylphenylpolysiloxane represented by thefollowing average unit formula:

(MeViSiO_(2/2))_(0.25)(Ph₂SiO_(2/2))_(0.3)(PhSiO_(3/2))_(0.45)(HO_(1/2))_(0.04)

37.5 parts by mass of phenyltris(dimethylvinylsiloxy)silane representedby the following formula:

(ViMe₂SiO)₃SiPh

80 parts by mass of 1,1,5,5-tetramethyl-3,3-diphenyltrisiloxanerepresented by the following formula:

(HMe₂SiO)₂SiPh₂

in an amount that provides 0.89 moles of silicon atom-bonded hydrogenatoms in the present component per 1 mole of the total amount of vinylgroups in the aforementioned methylvinylphenylpolysiloxane andphenyltris(dimethylvinylsiloxy)silane, 10 parts by mass of apolysiloxane represented by the following formula:

Me₃SiO(MeHSiO)₁₂SiMe₃

in an amount that provides 0.37 moles of silicon atom-bonded hydrogenatoms in the present component per 1 mole of the total amount of vinylgroups in the aforementioned methylvinylphenylpolysiloxane andphenyltris(dimethylvinylsiloxy)silane,1,3-divinyl-1,1,3,3-tetramethyldisiloxane solution of1,3-divinyl-1,1,3,3-tetramethyldisiloxane complex of platinum in anamount that provides 3.5 ppm of platinum metal in terms of mass units inthe present composition, 1-ethynyl-1-cyclohexanol in an amount thatprovides 200 ppm in terms of mass units in the present composition, 80parts by mass of titanium oxide having an average primary particlediameter of 0.24 μm (TIPAQUE R-630, manufactured by Ishihara SangyoKaisha Ltd.), 65 parts by mass of crushed quartz powder having anaverage particle diameter of 5 μm (MIN-U-SIL #5, manufactured by HayashiKasei Co., Ltd.), and 135 parts by mass of spherical silica having 30 μmaverage particle diameter (FB-570, manufactured by Denki Kagaku KogyoK.K.) were blended to prepare a curable silicone composition that had aviscosity of 9.2 Pa·s.

This composition was heated for 2 hours at 150° C. to form a curedproduct. This cured product had a type D durometer hardness of 80, abending strength of 21 MPa, a total luminous reflectance of 94.5%, and alinear expansion coefficient of 94 ppm/° C. The optical semiconductordevice shown in FIG. 1 was produced using this composition. Flashing andvoids were not observed in this optical semiconductor device. No peelingwas observed of the sealing agent from the light reflection material inoptical semiconductor devices using either OE-6370HF or OE-6630 as thesealing agent materials.

Practical Example 3

100 parts by mass of a methylvinylphenylpolysiloxane represented by thefollowing average unit formula:

(MeViSiO_(2/2))_(0.10)(Me₂SiO_(2/2))_(0.15)(PhSiO_(3/2))_(0.75)(HO_(1/2))_(0.01)

37.5 parts by mass of tetrakis(dimethylvinylsiloxy)silane represented bythe following formula:

(ViMe₂SiO)₄Si

70 parts by mass of 1,1,5,5-tetramethyl-3,3-diphenyltrisiloxanerepresented by the following formula:

(HMe₂SiO)₂SiPh₂

in an amount that provides 0.84 moles of silicon atom-bonded hydrogenatoms in the present component per 1 mole of the total amount of vinylgroups in the aforementioned methylvinylphenylpolysiloxane andtetrakis(dimethylvinylsiloxy)silane, 15 parts by mass of a polysiloxanerepresented by the following formula:

Me₃SiO(MeHSiO)₃₀(Me₂SiO)₃₀SiMe₃

in an amount that provides 0.31 moles of silicon atom-bonded hydrogenatoms in the present component per 1 mole of the total amount of vinylgroups in the aforementioned methylvinylphenylpolysiloxane andtetrakis(dimethylvinylsiloxy)silane,1,3-divinyl-1,1,3,3-tetramethyldisiloxane solution of1,3-divinyl-1,1,3,3-tetramethyldisiloxane complex of platinum in anamount that provides 3.5 ppm of the platinum metal in terms of massunits in the present composition, 1-ethynyl-1-cyclohexanol in an amountthat provides 200 ppm in terms of mass units in the present composition,80 parts by mass of titanium oxide having an average primary particlediameter of 0.24 μm (TIPAQUE R-630, manufactured by Ishihara SangyoKaisha Ltd.), 65 parts by mass of milled glass fiber having 20 μmaverage cut length and 3 μm average fiber diameter (MF03JB 1-20,manufactured by Asahi Fiber Glass Co., Ltd.), and 135 parts by mass ofspherical silica having 15 μm average particle diameter (HS-202,manufactured by Nippon Steel & Sumikin Materials Co., Ltd.) were blendedto prepare a curable silicone composition that had a viscosity of 7.7Pa·s.

This composition was heated for 2 hours at 150° C. to form a curedproduct. This cured product had a type D durometer hardness of 77, abending strength of 8.3 MPa, a total luminous reflectance of 94.6%, anda linear expansion coefficient of 123 ppm/° C. The optical semiconductordevice shown in FIG. 1 was produced using this composition. Flashing andvoids were not observed in this optical semiconductor device. Althoughpeeling was not observed for the sealing agent from the light reflectionmaterial when OE-6370HF was used as the sealing agent of the opticalsemiconductor device, in 2 out of 20 optical semiconductor devices,peeling of the sealing agent from the light reflection material wasobserved when OE-6630 was used as the sealing agent.

Practical Example 4

100 parts by mass of a methylvinylphenylpolysiloxane represented by thefollowing average unit formula:

(Me₂ViSiO_(1/2))_(0.20)(PhSiO_(3/2))_(0.80)(HO_(1/2))_(0.02)

8 parts by mass of1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane represented bythe following formula:

(MeViSiO)₄

20 parts by mass of a dimethylvinylsiloxy-terminatedpolymethylphenylsiloxane represented by the following formula:

ViMe₂SiO(MePhSiO)_(17.5)SiViMe₂

30 parts by mass of 1,1,5,5-tetramethyl-3,3-diphenyltrisiloxanerepresented by the following formula:

(HMe₂SiO)₂SiPh₂

in an amount that provides 0.66 moles of silicon atom-bonded hydrogenatoms in the present component per 1 mole of the total amount of vinylgroups in the aforementioned methylvinylphenylpolysiloxane,1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane, anddimethylvinylsiloxy-terminated polymethylphenylsiloxane, 2.5 parts bymass of a silicon atom-bonded hydrogen atom-containingmethylphenylpolysiloxane represented by the following average unitformula:

(Me₂HSiO_(1/2))_(0.6)(PhSiO_(3/2))_(0.4)

in an amount that provides 0.06 moles of silicon atom-bonded hydrogenatoms in the present component per 1 mole of the total amount of vinylgroups in the aforementioned methylvinylphenylpolysiloxane,1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane, anddimethylvinylsiloxy-terminated polymethylphenylsiloxane, 3.5 parts bymass of 1,3,5,7-tetramethylcyclotetrasiloxane represented by thefollowing formula:

(MeHSiO)₄

in an amount that provides 0.50 moles of silicon atom-bonded hydrogenatoms in the present component per 1 mole of the total amount of vinylgroups in the aforementioned methylvinylphenylpolysiloxane,1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane, anddimethylvinylsiloxy-terminated polymethylphenylsiloxane,1,3-divinyl-1,1,3,3-tetramethyldisiloxane solution of1,3-divinyl-1,1,3,3-tetramethyldisiloxane complex of platinum in anamount that provides 5 ppm of the platinum metal in terms of mass unitsin the present composition, 1-ethynyl-1-cyclohexanol in an amount thatprovides 250 ppm in terms of mass units in the present composition, 110parts by mass of titanium oxide having an average primary particlediameter of 0.2 μm (SX-3103, manufactured by Sakai Chemical IndustryCo., Ltd.), 100 parts by mass of crushed quartz powder having an averageparticle diameter of 5 μm (SILICIC SAB-500, manufactured by YamamoriTsuchimoto Mining Co., Ltd.), and 180 parts by mass of spherical silicahaving 15 μm average particle diameter (HS-202, manufactured by NipponSteel & Sumikin Materials Co., Ltd.) were blended to prepare a curablesilicone composition that had a viscosity of 89 Pa·s.

This composition was heated for 2 hours at 150° C. to form a curedproduct. This cured product had a type D durometer hardness of 85, abending strength of 19 MPa, a total luminous reflectance of 95.6%, and alinear expansion coefficient of 76 ppm/° C. The optical semiconductordevice shown in FIG. 1 was produced using this composition. Flashing andvoids were not observed in this optical semiconductor device. No peelingwas observed of the sealing agent from the light reflection material inoptical semiconductor devices using either OE-6370HF or OE-6630 as thesealing agent materials.

Comparative Example 1

100 parts by mass of a methylvinylphenylpolysiloxane represented by thefollowing average unit formula:

(MeViSiO_(2/2))_(0.15)(Me₂SiO_(2/2))_(0.15)(Ph₂SiO_(2/2))_(0.30)(PhSiO_(3/2))_(0.40)(HO_(1/2))_(0.04)

25 parts by mass of1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane represented bythe following formula:

(MeViSiO)₄

56 parts by mass of 1,1,5,5-tetramethyl-3,3-diphenyltrisiloxanerepresented by the following formula:

(HMe₂SiO)₂SiPh₂

in an amount that provides 0.91 moles of silicon atom-bonded hydrogenatoms in the present component per 1 mole of the total amount of vinylgroups in the aforementioned methylvinylphenylpolysiloxane and1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane,1,3-divinyl-1,1,3,3-tetramethyldisiloxane solution of1,3-divinyl-1,1,3,3-tetramethyldisiloxane complex of platinum in anamount that provides 3.5 ppm of the platinum metal in terms of massunits in the present composition, 1-ethynyl-1-cyclohexanol in an amountthat provides 200 ppm in terms of mass units in the present composition,100 parts by mass of titanium oxide having an average primary particlediameter of 0.2 μm (SX-3103, manufactured by Sakai Chemical IndustryCo., Ltd.), 135 parts by mass of crushed quartz powder having an averageparticle diameter of 5 μm (CRYSTALITE VX-52, manufactured by TatsumoriLtd.), and 110 parts by mass of spherical silica having 15 μm averageparticle diameter (HS-202, manufactured by Nippon Steel & SumikinMaterials Co., Ltd.) were blended to prepare a curable siliconecomposition that had a viscosity of 39 Pa·s.

This composition was heated for 2 hours at 150° C. to form a curedproduct. This cured product had a type D durometer hardness of 75, abending strength of 7.0 MPa, a total luminous reflectance of 94.5%, anda linear expansion coefficient of 121 ppm/° C. The optical semiconductordevice shown in FIG. 1 was produced using this composition. Flashing andvoids were not observed in this optical semiconductor device. In 5 of 20optical semiconductor devices produced by using OE-6370HF as the sealingagent, peeling of the sealing agent from the light reflection materialwas observed. In all 20 optical semiconductor devices produced by usingOE-6630 as the sealing agent, peeling of the sealing agent from thelight reflection material was observed.

Comparative Example 2

100 parts by mass of a methylvinylphenylpolysiloxane represented by thefollowing average unit formula:

(MeViSiO_(2/2))_(0.25)(Ph₂SiO_(2/2))_(0.3)(PhSiO_(3/2))_(0.45)(HO_(1/2))_(0.04)

37.5 parts by mass of phenyltris(dimethylvinylsiloxy)silane representedby the following formula:

(ViMe₂SiO)₃SiPh

87 parts by mass of 1,1,5,5-tetramethyl-3,3-diphenyltrisiloxanerepresented by the following formula:

(HMe₂SiO)₂SiPh₂

in an amount that provides 0.97 moles of silicon atom-bonded hydrogenatoms in the present component per 1 mole of the total amount of vinylgroups in the aforementioned methylvinylphenylpolysiloxane andphenyltris(dimethylvinylsiloxy)silane, 10 parts by mass of a siliconatom-bonded hydrogen atom-containing methylphenylpolysiloxanerepresented by the following average unit formula:

(Me₂HSiO_(u2))_(0.6)(PhSiO_(3/2))_(0.4)

in an amount that provides 0.12 moles of silicon atom-bonded hydrogenatoms in the present component per 1 mole of the total amount of vinylgroups in the aforementioned methylvinylphenylpolysiloxane andphenyltris(dimethylvinylsiloxy)silane,1,3-divinyl-1,1,3,3-tetramethyldisiloxane solution of1,3-divinyl-1,1,3,3-tetramethyldisiloxane complex of platinum in anamount that provides 3.5 ppm of the platinum metal in terms of massunits in the present composition, 1-ethynyl-1-cyclohexanol in an amountthat provides 200 ppm in terms of mass units in the present composition,80 parts by mass of titanium oxide having an average primary particlediameter of 0.24 μm (TIPAQUE R-630, manufactured by Ishihara SangyoKaisha Ltd.), 65 parts by mass of crushed quartz powder having anaverage particle diameter of 5 μm (MIN-U-SIL #5, manufactured by HayashiKasei Co., Ltd.), and 135 parts by mass of spherical silica having 30 μmaverage particle diameter (FB-570, manufactured by Denki Kagaku KogyoK.K.) were blended to prepare a curable silicone composition that had aviscosity of 9.4 Pa·s.

This composition was heated for 2 hours at 150° C. to form a curedproduct. This cured product had a type D durometer hardness of 80, abending strength of 21 MPa, a total luminous reflectance of 94.5%, and alinear expansion coefficient of 94 ppm/° C. The optical semiconductordevice shown in FIG. 1 was produced using this composition. Flashing andvoids were not observed in this optical semiconductor device. In 7 of 20optical semiconductor devices produced by using OE-6370HF as the sealingagent, peeling of the sealing agent from the light reflection materialwas observed. In all 20 optical semiconductor devices produced by usingOE-6630 as the sealing agent, peeling of the sealing agent from thelight reflection material was observed.

Comparative Example 3

100 parts by mass of a methylvinylphenylpolysiloxane represented by thefollowing average unit formula:

(MeViSiO_(2/2))_(0.10)(Me₂SiO_(2/2))_(0.15)(PhSiO_(3/2))_(0.75)(HO_(1/2))_(0.01)

37.5 parts by mass of tetrakis(dimethylvinylsiloxy)silane represented bythe following formula:

(ViMe₂SiO)₄Si

70 parts by mass of 1,1,5,5-tetramethyl-3,3-diphenyltrisiloxanerepresented by the following formula:

(HMe₂SiO)₂SiPh₂

in an amount that provides 0.84 moles of silicon atom-bonded hydrogenatoms in the present component per 1 mole of the total amount of vinylgroups in the aforementioned methylvinylphenylpolysiloxane andtetrakis(dimethylvinylsiloxy)silane, 25 parts by mass of a polysiloxanerepresented by the following formula:

Me₃SiO(MeHSiO)₂₀(Me₂SiO)₄₀SiMe₃

in an amount that provides 0.32 moles of silicon atom-bonded hydrogenatoms in the present component per 1 mole of the total amount of vinylgroups in the aforementioned methylvinylphenylpolysiloxane andtetrakis(dimethylvinylsiloxy)silane,1,3-divinyl-1,1,3,3-tetramethyldisiloxane solution of1,3-divinyl-1,1,3,3-tetramethyldisiloxane complex of platinum in anamount that provides 3.5 ppm of the platinum metal in terms of massunits in the present composition, 1-ethynyl-1-cyclohexanol in an amountthat provides 200 ppm in terms of mass units in the present composition,80 parts by mass of titanium oxide having an average primary particlediameter of 0.24 μM (TIPAQUE R-630, manufactured by Ishihara SangyoKaisha Ltd.), 65 parts by mass of milled glass fiber having 20 μmaverage cut length and 3 μm average fiber diameter (MF03JB 1-20,manufactured by Asahi Fiber Glass Co., Ltd.), and 135 parts by mass ofspherical silica having 15 μM average particle diameter (HS-202,manufactured by Nippon Steel & Sumikin Materials Co., Ltd.) were blendedto prepare a curable silicone composition that had a viscosity of 7.5Pa·s.

This composition was heated for 2 hours at 150° C. to form a curedproduct. This cured product had a type D durometer hardness of 75, abending strength of 7.6 MPa, a total luminous reflectance of 94.5%, anda linear expansion coefficient of 120 ppm/° C. The optical semiconductordevice shown in FIG. 1 was produced using this composition. Althoughflashing and voids were not observed in this optical semiconductordevice, partial cracking was observed. In 3 of 20 optical semiconductordevices produced by using OE-6370HF as the sealing agent, peeling of thesealing agent from the light reflection material was observed. In 17 of20 optical semiconductor devices produced by using OE-6630 as thesealing agent, peeling of the sealing agent from the light reflectionmaterial was observed.

Comparative Example 4

100 parts by mass of a methylvinylphenylpolysiloxane represented by thefollowing average unit formula:

(Me₂ViSiO_(1/2))_(0.20)(PhSiO_(3/2))_(0.80)(HO_(1/2))_(0.02)

8 parts by mass of1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane represented bythe following formula:

(MeViSiO)₄

20 parts by mass of a dimethylvinylsiloxy-terminatedpolymethylphenylsiloxane represented by the following formula:

ViMe₂SiO(MePhSiO)_(17.5)SiViMe₂

40 parts by mass of 1,1,5,5-tetramethyl-3,3-diphenyltrisiloxanerepresented by the following formula:

(HMe₂SiO)₂SiPh₂

in an amount that provides 0.88 moles of silicon atom-bonded hydrogenatoms in the present component per 1 mole of the total amount of vinylgroups in the aforementioned methylvinylphenylpolysiloxane,1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane, anddimethylvinylsiloxy-terminated polymethylphenylsiloxane, 5 parts by massof a silicon atom-bonded hydrogen atom-containingmethylphenylpolysiloxane represented by the following average unitformula:

(Me₂HSiO_(1/2))_(0.6)(PhSiO_(3/2))_(0.4)

in an amount that provides 0.12 moles of silicon atom-bonded hydrogenatoms in the present component per 1 mole of the total amount of vinylgroups in the aforementioned methylvinylphenylpolysiloxane,1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane, anddimethylvinylsiloxy-terminated polymethylphenylsiloxane, 1.0 parts bymass of 1,3,5,7-tetramethylcyclotetrasiloxane represented by thefollowing formula:

(MeHSiO)₄

in an amount that provides 0.14 moles of silicon atom-bonded hydrogenatoms in the present component per 1 mole of the total amount of vinylgroups in the aforementioned methylvinylphenylpolysiloxane,1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane, anddimethylvinylsiloxy-terminated polymethylphenylsiloxane,1,3-divinyl-1,1,3,3-tetramethyldisiloxane solution of1,3-divinyl-1,1,3,3-tetramethyldisiloxane complex of platinum in anamount that provides 5 ppm of the platinum metal in terms of mass unitsin the present composition, 1-ethynyl-1-cyclohexanol in an amount thatprovides 250 ppm in terms of mass units in the present composition, 110parts by mass of titanium oxide having an average primary particlediameter of 0.2 μm (SX-3103, manufactured by Sakai Chemical IndustryCo., Ltd.), 100 parts by mass of crushed quartz powder having an averageparticle diameter of 5 μm (SILICIC SAB-500, manufactured by YamamoriTsuchimoto Mining Co., Ltd.), and 250 parts by mass of spherical silicahaving 15 μm average particle diameter (HS-202, manufactured by NipponSteel & Sumikin Materials Co., Ltd.) were blended to prepare a curablesilicone composition that had a viscosity of 97 Pa·s.

This composition was heated for 2 hours at 150° C. to form a curedproduct. This cured product had a type D durometer hardness of 85, abending strength of 19 MPa, a total luminous reflectance of 95.5%, and alinear expansion coefficient of 75 ppm/° C. The optical semiconductordevice shown in FIG. 1 was produced using this composition. Flashing andvoids were not observed in this optical semiconductor device. In 7 of 20optical semiconductor devices produced by using OE-6370HF as the sealingagent, peeling of the sealing agent from the light reflection materialwas observed. In all 20 optical semiconductor devices produced by usingOE-6630 as the sealing agent, peeling of the sealing agent from thelight reflection material was observed.

Comparative Example 5

100 parts by mass of a methylvinylphenylpolysiloxane represented by thefollowing average unit formula:

(Me₂ViSiO_(1/2))_(0.20)(PhSiO_(3/2))_(0.80)(HO_(1/2))_(0.02)

8 parts by mass of1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane represented bythe following formula:

(MeViSiO)₄

20 parts by mass of a dimethylvinylsiloxy-terminatedpolymethylphenylsiloxane represented by the following formula:

ViMe₂SiO(MePhSiO)_(17.5)SiViMe₂

20 parts by mass of 1,1,5,5-tetramethyl-3,3-diphenyltrisiloxanerepresented by the following formula:

(HMe₂SiO)₂SiPh₂

in an amount that provides 0.66 moles of silicon atom-bonded hydrogenatoms in the present component per 1 mole of the total amount of vinylgroups in the aforementioned methylvinylphenylpolysiloxane,1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane, anddimethylvinylsiloxy-terminated polymethylphenylsiloxane, 6 parts by massof 1,3,5,7-tetramethyl cyclotetrasiloxane represented by the followingformula:

(MeHSiO)₄

in amount that provides 0.88 moles of silicon atom-bonded hydrogen atomsin the present component per 1 mole of the total amount of vinyl groupsin the aforementioned methylvinylphenylpolysiloxane,1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane, anddimethylvinylsiloxy-terminated polymethylphenylsiloxane,1,3-divinyl-1,1,3,3-tetramethyldisiloxane solution of1,3-divinyl-1,1,3,3-tetramethyldisiloxane complex of platinum in anamount that provides 5 ppm of the platinum metal in terms of mass unitsin the present composition, 1-ethynyl-1-cyclohexanol in an amount thatprovides 250 ppm in terms of mass units in the present composition, 110parts by mass of titanium oxide having an average primary particlediameter of 0.2 μm (SX-3103, manufactured by Sakai Chemical IndustryCo., Ltd.), 100 parts by mass of crushed quartz powder having an averageparticle diameter of 5 μm (SILICIC SAB-500, manufactured by YamamoriTsuchimoto Mining Co., Ltd.), and 250 parts by mass of spherical silicahaving 15 μM average particle diameter (HS-202, manufactured by NipponSteel & Sumikin Materials Co., Ltd.) were blended to prepare a curablesilicone composition that had a viscosity of 80 Pa·s.

This composition was heated for 2 hours at 150° C. to form a curedproduct. This cured product had a type D durometer hardness of 90, abending strength of 8.2 MPa, a total luminous reflectance of 95.3%, anda linear expansion coefficient of 70 ppm/° C. The optical semiconductordevice shown in FIG. 1 was produced using this composition. Althoughflashing and voids were not observed in this optical semiconductordevice, partial cracking was observed. Although peeling was not observedfor the sealing agent from the light reflection material when OE-6370HFwas used as the sealing agent of the optical semiconductor device, in 6out of 20 optical semiconductor devices, peeling of the sealing agentfrom the light reflection material was observed when OE-6630 was used asthe sealing agent.

INDUSTRIAL APPLICABILITY

The curable silicone composition of the present invention has goodformability and forms a cured product that is resistant to theoccurrence of discoloration and lowering of mechanical strength by heatand light. Adhesion to this cured product by the sealing agent used fora semiconductor device is good, and thus the curable siliconecomposition of the present invention is suitable as a material for thewhite casing material of a light emitting diode.

DESCRIPTION OF SYMBOLS

-   -   1 optical semiconductor element    -   2 lead frame    -   3 lead frame    -   4, 4′ bonding wire    -   5 light reflection material composed of cured silicone    -   6 sealing agent

1. A curable silicone composition comprising: (A) 100 parts by mass ofan organopolysiloxane represented by the following average unit formula:(R¹ ₃SiO_(1/2))_(a)(R¹₂SiO_(2/2))_(b)(R¹SiO_(3/2))_(c)(SiO_(4/2))_(d)(R²O_(1/2))_(e) whereinR¹ are independently the same or different, and are phenyl groups, alkylgroups having from 1 to 6 carbons, or alkenyl groups having from 2 to 6carbons, provided that 30 to 80 mole % of all R¹ are phenyl groups, and5 to 20 mole % of all R¹ are alkenyl groups; R² is a hydrogen atom oralkyl group having from 1 to 6 carbons; and a, b, c, d, and e arenumbers that respectively satisfy: 0≦a≦0.3, 0≦b≦0.7, 0.3≦c≦0.9, 0≦d≦0.1,0≦e≦0.1, and a+b+c+d=1; (B) 5 to 50 parts by mass of anorganopolysiloxane having 10 or less silicon atoms, wherein 30 to 60mole % of all silicon atom-bonded organic groups in the (B) componentare alkenyl groups having from 2 to 6 carbons; (c) 0 to 40 parts by massof an organopolysiloxane represented by the following general formula:R³ ₃SiO(R³ ₂SiO)_(m)SiR³ ₃ wherein R³ are independently the same ordifferent, and are phenyl groups, alkyl groups having from 1 to 6carbons, or alkenyl groups having from 2 to 6 carbons, provided that 30to 70 mole % of all R³ are phenyl groups, and at least one R³ is analkenyl group; and m is an integer in a range from 10 to 100; (D) anorganopolysiloxane having at least 2 silicon atom-bonded hydrogen atomsin a molecule, wherein the content of phenyl groups in all siliconatom-bonded organic groups in this component is at least 20 mole %, inan amount that provides 0.3 to 1.5 moles of the silicon atom-bondedhydrogen atoms in the (D) component per 1 mole of the total amount ofalkenyl groups in components (A) to (C); (E) an organopolysiloxanehaving at least 2 silicon atom-bonded hydrogen atoms in a molecule,wherein the content of phenyl groups in all silicon atom-bonded organicgroups in the (E) component is less than 20 mole %, in an amount thatprovides 0.2 to 0.8 moles of the silicon atom-bonded hydrogen atoms inthe (E) component per 1 mole of the total amount of alkenyl groups incomponents (A) to (C); (F) a hydrosilylation reaction catalyst in anamount sufficient to accelerate a hydrosilylation reaction between thealkenyl groups in components (A) to (C) and the silicon atom-bondedhydrogen atoms in components (D) and (E); (G) a white pigment in anamount of at least 25 parts by mass per 100 parts by mass of the totalamount of components (A) to (F); and (H) an inorganic filler other thana white pigment in an amount of at least 40 parts by mass per 100 partsby mass of the total amount of components (A) to (F), wherein thecontent of the total amount of components (G) and (H) is not more than300 parts by mass per 100 parts by mass of the total amount ofcomponents (A) to (F).
 2. The curable silicone composition according toclaim 1, wherein component (D) is an organopolysiloxane in which 20 to70 mole % of all silicon atom-bonded organic groups are phenyl groups.3. The curable silicone composition according to claim 1, whereincomponent (E) is an organopolysiloxane in which 90 mole % or more of allsilicon atom-bonded organic groups are methyl groups.
 4. The curablesilicone composition according to claim 1, wherein the total amount ofthe silicon atom-bonded hydrogen atoms in components (D) and (E) per 1mole of the total amount of alkenyl groups in components (A) to (C) isfrom 0.5 to 2.0 moles.
 5. The curable silicone composition according toclaim 1, wherein a viscosity at 25° C. is from 5 to 200 Pa·s.
 6. Thecurable silicone composition according to claim 1, wherein the curablesilicone composition cures to form a cured product having a type Ddurometer hardness greater than or equal to 60, and a bending strengthgreater than or equal to 5 MPa.
 7. The curable silicone compositionaccording to claim 1, wherein the curable silicone composition cures toform a cured product having a total luminous reflectance greater than orequal to 80%.
 8. The curable silicone composition according to claim 1,wherein the curable silicone composition cures to form a cured producthaving an average coefficient of linear expansion in a temperature rangeof 25 to 200° C. less than or equal to 200 ppm/° C.
 9. A cured productproduced by curing the curable silicone composition according toclaim
 1. 10. An optical semiconductor device comprising: an opticalsemiconductor element a light reflection material for reflecting lightemitted from the element and a sealing agent for sealing the elementthat contacts the light reflection material, wherein the lightreflection material is formed by a cured product of the curable siliconecomposition according to claim 1.